chdkcamera: Fix check for supported zoom levels
chdkcamera: Fix check for supported zoom levels

jbaiter/spreads,DIYBookScanner/spreads,jbaiter/spreads,DIYBookScanner/spreads,nafraf/spreads,miloh/spreads,gareth8118/spreads,adongy/spreads,gareth8118/spreads,nafraf/spreads,adongy/spreads,gareth8118/spreads,adongy/spreads,jbaiter/spreads,miloh/spreads,miloh/spreads,nafraf/spreads,DIYBookScanner/spreads